概述
数据手册SM8303-ADJ 概述
150KHz, 3A PWM Buck Switching Regulator 为150KHz ， 3A PWM降压型开关稳压器
SM8303-ADJ 数据手册
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PDF下载SAMHOP Microelectronics Corp.
SM8303
150KHz, 3A PWM Buck Switching Regulator
ꢀ General Description
ꢀ Features
The SM8303 is a monolithic integrated circuit that
provide all the active functions for a step-down
switching regulator, capable of driving a 3A load
without additional transistor component. Requiring
a minimum number of external component, the
board space can be saved easily. The external
shutdown function can be controlled by TTL logic
level and then come into standby mode. The
internal compensation makes feedback control
have good line and load regulation without external
design. Regarding protected function, thermal
shutdown is to prevent over temperature operating
from damage, and current limit is against over
current operating of the output switch. The SM8303
operates at a switching frequency of 150KHz thus
allowing smaller sized filter components than what
would be needed with lower frequency switching
regulators. Other features include a guaranteed
+4% tolerance on output voltage under specified
input voltage and output load conditions, and +15%
on the oscillator frequency. The output version
included fixed 3.3V, 5V, 12V, and an adjustable
type. The packages are available in a standard
5-lead TO-220(T) package and a 5-lead TO-263(S).
- 3.3V, 5V, 12V and adjustable output versions
- Adjustable version output voltage range, 1.23V to
28V +4% max over line and load condition
- Available in TO220-5L and TO263-5L packages
- Voltage mode non-synchronous PWM control
- Thermal-shutdown and current-limit protection
- ON/OFF shutdown control input
- Input voltage range up to 32V
- Output load current: 3A
- 150KHz fixed frequency internal oscillator
- Low power standby mode
- Built-in switching transistor on chip
ꢀ Applications
- Simple High-efficiency step-down(buck) regulator
- Efficient preregulator for linear regulators
- On-card switching regulators
- Positive to negative converter
- Battery Charger
ꢀPin Assignments
ꢀ Pin Descriptions
( Top View )
5 SD
4 FB
3 Gnd
2 Output
1 VIN
Name
VIN
Description
Operating voltage input
Switching output
Output
Gnd
FB
Metal Tab GND
Ground
TO263-5L
Output voltage feedback control
ON/OFF Shutdown
( Top View )
SD
5 SD
4 FB
3 Gnd
2 Output
1 VIN
TO220-5L
1
V1.0 May 17 ,2007
SAMHOP Microelectronics Corp.
SM8303
150KHz, 3A PWM Buck Switching Regulator
ꢀ Ordering Information
XX X X
SM8303
Package
Output version
Packing
Blank : Tube
-ADJ : Adjustable
-33 : 3.3V
T: TO220-5L
S: TO263-5L
A
: Taping
-50 : 5.0V
-12 : 12V
ꢀ Block Diagram
SD
VIN
200mV
220mV
Current
Source
bias
1.235V
Reference
2.5V
Regulator
Start
up
+
Comp
_
_
Comp
+
+
_
Amp
3A
Switch
_
Comp
+
Pre-driver
FB
Output
Gnd
150kHz
OSC.
Thermal
Limit
2
V1.0 May 17 ,2007
SAMHOP Microelectronics Corp.
SM8303
150KHz, 3A PWM Buck Switching Regulator
ꢀ Absolute Maximum Ratings
Symbol
Parameter
Rating
+35
Unit
V
VCC
Supply Voltage
VSD
ON/OFF Pin input voltage
Feedback Pin voltage
Output voltage to Ground
Power dissipation
-0.3 to +25
-0.3 to +25
-1
V
VFB
V
VOUT
PD
V
Internally limited
-65 to +150
-40 to +125
+4.5 to +25
W
oC
oC
V
TST
Storage temperature
Operating temperature
Operating voltage
TOP
VOP
ꢀ Electrical Characteristics (All Output Voltage Versions)
Unless otherwise specified, VIN=12V for 3.3V, 5V, adjustable version and VIN=24V for the 12V version. ILOAD = 0.3A
Symbol
Parameter
Conditions
Min.
Typ.
40
Max.
60
Unit
VFB=1.3V
(Adjustable version only)
IB
Feedback bias current
nA
100
173
173
1.4
127
150
FOSC
VSAT
DC
oscillator frequency
saturation voltage
Khz
V
110
IOUT=3A
1.3
no outside circuit
VFB=0V force driver on
1.5
Max. Duty Cycle(ON)
Min. Duty cycle(OFF)
VFB=0V force driver on
VFB=12V force driver off
100
0
%
peak current
5.5
6.5
ICL
current limit
no outside circuit
VFB=0 force driver on
no outside circuit
VFB=12 force driver off
3.6
4.5
A
Output
leakage
Output = 0V
200
uA
IL
current
Output= -1V
VIN=32V
2
5
60
10
mA
mA
IQ
ISTBY
VIL
Quiescent Current
VFB=12 force driver off
250
300
0.6
Standby Quiescent
Current
ON/OFF pin=5V
VIN=24V
150
uA
Low (regulator ON)
High (regulator OFF)
-
ON/OFF pin logic input
threshold voltage
1.3
15
V
VIH
2.0
-
ON/OFF pin logic
input current
IH
IL
VLOGIC=2.5V (OFF)
25
5
uA
ON/OFF pin input current VLOGIC=0.5V (ON)
0.02
2.5
3.5
28
TO220-5L
TO263-5L
TO220-5L
Junction to
case
Thermal Resistance
oC/W
oC/W
ΘJC
Thermal Resistance
With copper area of
approximately 3 in2
Junction to
ambient
ΘJA
TO263-5L
23
3
V1.0 May 17 ,2007
SAMHOP Microelectronics Corp.
SM8303
150KHz, 3A PWM Buck Switching Regulator
ꢀ Electrical Characteristics (Continued)
Symbol
Parameter
Conditions
Typ.
Limit
Unit
5V < VIN < 32V
0.2A < ILOAD < 3A
VOUT programmed for
3V
V
VMIN
VMAX
Output
Feedback
VFB
1.23
1.193/1.18
1.267/1.28
SM8303-ADJ
η
Efficiency
Output voltage
Efficiency
VIN = 12V, ILOAD=3A
73
3.3
73
5
%
V
VMIN
VMAX
5.5V < VIN < 32V
0.2A < ILOAD < 3A
3.168/3.135
3.432/3.465
VOUT
SM8303-3.3V
SM8303-5V
SM8303-12V
η
VIN = 12V, ILOAD=3A
%
V
VMIN
VMAX
8V < VIN < 32V
0.2A < ILOAD < 3A
4.8/4.75
5.2/5.25
VOUT
Output voltage
Efficiency
η
VIN = 12V, ILOAD=3A
80
12
90
%
V
VMIN
VMAX
15V < VIN < 32V
0.2A < ILOAD < 3A
11.52/11.4
12.48/12.6
VOUT
Output voltage
Efficiency
η
VIN = 15V, ILOAD = 3A
%
Specifications with boldface type are for full operating temperature range, the other type are for TJ=25ºC.
4
V1.0 May 17 ,2007
SAMHOP Microelectronics Corp.
SM8303
150KHz, 3A PWM Buck Switching Regulator
ꢀTypical Performance Characteristics
Typical Performance Characteristics
Normalized Output Voltage
Efficiency
5.10
VIN =20V, I LOAD=3A
Normalized at TJ=25oC
100
3A Load
5.05
5.00
4.95
4.90
95
90
85
80
75
70
5V
3.3V
-50 -25
0
25
50 75 100 125
30
40
8
10 15
20
25
35
JUNCTION TEMPERATURE(oC)
JUNCTION TEMPERATURE(oC)
Switch Saturation Voltage
Switch Current Limit
8.0
6.0
4.0
2.0
0.0
1.7
1.6
1.5
1.4
1.3
1.2
1 : -40 oC
2 : 25 oC
3 : 125 oC
VIN
=10V 20V 40V
1
2
3
2.0
4
5
3
0
1
2
3
4
5
6
7
SWITCH CURRENT(A)
Output current Io (A)
Shutdown Quiescent Current
Operating Quiescent Current
200.0
130.0
100.0
80.0
40.0
0.0
25.0
20.0
15.0
10.0
5.0
Switch ON
1
2
VON/OFF=5V
1 : -40 oC
2 : 25 oC
3 : 125 oC
3
Switch OFF
0.0
-50 -25
0
25
50 75 100 125
10
20
30
40
JUNCTION TEMPERATURE(oC)
SUPPLY VOLOTAGE (V)
5
V1.0 May 17 ,2007
SAMHOP Microelectronics Corp.
SM8303
150KHz, 3A PWM Buck Switching Regulator
ꢀTypical Performance Characteristics (Continued)
ON/OFF Threshold Voltage
Minimum Operating Supply Voltage
5.0
4.0
3.0
2.0
1.0
0.0
5.0
4.0
3.0
2.0
1.0
0.0
VOUT =1.23V
ILOAD=120mA
-50 -25
0
25 50 75 100 125
-50 -25
0
25 50 75 100 125
JUNCTION TEMPERATURE ( oC)
JUNCTION TEMPERATURE ( oC)
Switch Frequency
ON/OFF Pin Current (Sinking )
68.0
150.0
VIN =40V
-40o C≤ T ≤ 125oC
j
120.0
90.0
60.0
30.0
0.0
51.0
34.0
17.0
0.0
-50 -25
0
25 50 75 100 125
1.4
5
10 15 20 22 23 24 25
ON/OFF PIN VOLTAGE(V)
JUNCTION TEMPERATURE ( oC)
Feedback Pin Bias Current
Thermal protection
50.0
40.0
30.0
20.0
10.0
0.0
10
8
6
4
Adjustable Version Only
2
0
TSC OFF
TSD ON
50
75
100 125
150 175
200
-50 -25
0
25
50 75
100 125
JUNCTION TEMPERATURE( o C)
JUNCTION TEMPERATURE( oC)
6
V1.0 May 17 ,2007
SAMHOP Microelectronics Corp.
SM8303
150KHz, 3A PWM Buck Switching Regulator
ꢀTypical Application Circuit
（A） Fixed Type Circuit
FB
12V
DC Input
4
3.3V/3A
Output Load
L1
Output
1
2
SM8303
Vin
Inductor
5
3
SD
Gnd
Cin
Capacitor
Co
Capacitor
D1
Schottky Diode
(B) Adjustable Type Circuit
R2
R1
FB
12V
DC Input
4
3.3V/3A
Output Load
L1
Output
SM8303
1
2
Vin
68uF
5
3
Gnd
SD
Cin
Co
D1
680uF
1000uF
1N5824
Vout = VFB x (1+ R1/R2 )
VFB=1.23V
7
V1.0 May 17 ,2007
SAMHOP Microelectronics Corp.
SM8303
150KHz, 3A PWM Buck Switching Regulator
all approximate and there are many factors that can
affect these temperatures. Higher ambient
temperatures require more heat sinking.
The TO-263 surface mount package tab is
designed to be soldered to the copper on a printed
circuit board. The copper and the board are the
heat sink
for this package and the other heat producing
components, such as the catch diode and inductor.
The PC board copper area that the package is
soldered to should be at least 0.8 in2, and ideally
should have 2 or more square inches of 2 oz.
Additional copper area improves the thermal
characteristics, but with copper areas greater than
approximately 6 in2, only small improvements in
heat dissipation are realized. If further thermal
improvements are needed, double sided, multilayer
PC board with large copper areas and/or airflow are
recommended.
ꢀFunction Description
Pin Functions
+VIN
This is the positive input supply for the IC switching
regulator. A suitable input bypass capacitor must be
present at this pin to minimize voltage transients
and to supply the switching currents needed by the
regulator.
Output
Internal switch and power output. The voltage at
this pin switches between (+VIN – VSAT) and
approximately – 0.5V, with a duty cycle of
approximately VOUT / VIN. The PC board copper
area connected to this pin should be kept a
minimum in order to reduce the coupling sensitivity
to the circuitry
ꢀFunction Description (Continued)
Ground
Circuit ground.
The
SM8303
(TO-263
package)
junction
temperature rise above ambient temperature with a
2A load for various input and output voltages. This
data was taken with the circuit operating as a buck
switching regulator with all components mounted on
a PC board to simulate the junction temperature
under actual operating conditions. This curve can
be used for a quick check for the approximate
junction temperature for various conditions, but be
aware that there are many factors that can affect
the junction temperature. When load currents
higher than 3A are used, double sided or multilayer
PC boards with large copper areas and/or airflow
might be needed, especially for high ambient
temperatures and high output voltages.
Feedback
Complete the feedback loop by sensing the
regulated output voltage
ON/OFF
Allows the switching regulator circuit to be
shutdown using logic level signals thus dropping
the total input supply current to approximately
100uA. Pulling this pin below a threshold voltage of
approximately 1.3V turns the regulator on, and
pulling this pin above 1.3V (up to a maximum of
25V) shuts the regulator down. If this shutdown
feature is not needed, the ON /OFF pin can be
wired to the ground pin or it can be left open, in
either case the regulator will be in the ON condition.
For the best thermal performance, wide copper
traces and generous amounts of printed circuit
board copper should be used in the board layout.
(Once exception to this is the output (switch) pin,
which should not have large areas of copper.)
Large areas of copper provide the best transfer of
heat (lower thermal resistance) to the surrounding
Thermal Considerations
The SM8303 is available in two packages, a 5-pin
TO-220 and a 5-pin surface mount TO-263.
The TO-220 package needs a heat sink under most
conditions. The size of the heatsink depends on the
input voltage, the output voltage, the load current
and the ambient temperature. The SM8303 junction
temperature rises above ambient temperature for a
3A load and different input and output voltages.
The data for these curves was taken with the
SM8303 (TO-220 package) operating as a buck
switching regulator in an ambient temperature of
25oC (still air). These temperature rise numbers are
air, and moving air lowers the thermal resistance
even further.
Package
thermal
resistance
and
junction
temperature rise numbers are all approximate, and
there are many factors that will affect these
numbers. Some of these factors include board
8
V1.0 May 17 ,2007
SAMHOP Microelectronics Corp.
SM8303
150KHz, 3A PWM Buck Switching Regulator
size, shape, thickness, position, location, and even
board temperature. Other factors are, trace width,
total printed circuit copper area, copper thickness,
single or double-sided, multilayer board and the
amount of solder on the board. The effectiveness
of the PC board to dissipate heat also depends on
the size, quantity and spacing of other components
on the board, as well as whether the surrounding
air is still or moving. Furthermore, some of these
components such as the catch diode will add heat
to the PC board and the heat can vary as the input
voltage changes. For the inductor, depending on
the physical size, type of core material and the DC
resistance, it could either act as a heat sink taking
heat away from the board, or it could add heat to
the board.
ꢀMarking Information
(1) TO263-5L
(2) TO220-5L
( Top view )
( Top view )
Output Type:
8303-ADJ: ADJ
8303-33: 3.3V
8303-50: 5.0V
8303-12: 12V
Logo
SM
8303XX
YY WW ~
Output Type:
8303-ADJ: ADJ
8303-33: 3.3V
8303-50: 5.0V
8303-12: 12V
Logo
SM
8303-XX
YY WW ~
ID code
ID code
Xth week: 01~52
Year:
"03" = 2003
"04" = 2004
Xth week: 01~52
Year: "03" = 2003
"04" = 2004
9
V1.0 May 17 ,2007
SAMHOP Microelectronics Corp.
SM8303
150KHz, 3A PWM Buck Switching Regulator
ꢀ Package Information
(1) Package Type: TO220-5L
E
A
F
øP
e1
b
C
e
J1
Dimensions In Millimeters
Symbol
Dimensions In Inches
Min.
3.56
0.38
0.36
14.22
9.65
Max.
Min.
0.140
0.015
0.014
0.560
0.380
Max.
0.190
0.040
0.024
0.650
0.420
A
b
4.83
1.02
C
0.61
D
16.51
10.67
E
e
1.702 BSC
0.067 BSC
e1
F
6.858
0.508
5.84
8.89
1.397
6.86
0.270
0.020
0.230
0.080
0.520
0.139
0.100
0.350
0.055
0.270
0.115
0.580
0.161
0.135
H1
J1
L
2.03
2.92
12.70
3.53
14.73
4.10
øP
Q
2.54
3.43
10
V1.0 May 17 ,2007
SAMHOP Microelectronics Corp.
SM8303
150KHz, 3A PWM Buck Switching Regulator
ꢀPackage Information (Continued)
(2) Package Type: TO263-5L
E
F
A
C2
C
e
B
Dimensions In Millimeters
Dimensions In Inches
Symbol
Min.
4.064
0.508
0.381
1.143
8.382
9.652
Max.
4.826
0.991
0.737
1.651
9.652
10.668
Min.
0.160
0.020
0.015
0.045
0.330
0.380
Max.
0.190
0.039
0.029
0.065
0.380
0.420
A
B
C
C2
D
E
e
1.702 BSC
0.067 BSC
F
6.223
14.605
-
-
0.245
0.575
-
-
L
15.875
1.676
0.625
0.066
L1
11
V1.0 May 17 ,2007
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